"Fights between founders are surprisingly common. About 20% of the startups we've funded have had a founder leave." -Paul Graham http://www.paulgraham.com/start

"Fights between founders are surprisingly common. About 20% of the startups we've funded have had a founder leave." -Paul Graham http://www.paulgraham.com/startupmistakes.html http://www.paulgraham.com/startupmistakes.html Given that the YC pool should be higher quality than average, I'd assume the number to be significantly higher for the overall pool of startups.